Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2011 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.graphics; import org.eclipse.swt.*; import org.eclipse.swt.internal.cocoa.*; /** * Instances of this class represent transformation matrices for * points expressed as (x, y) pairs of floating point numbers. * <p> * Application code must explicitly invoke the <code>Transform.dispose()</code> * method to release the operating system resources managed by each instance * when those instances are no longer required. * </p> * <p> * This class requires the operating system's advanced graphics subsystem * which may not be available on some platforms. * </p> * * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: GraphicsExample</a> * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> * * @since 3.1 */ public class Transform extends Resource { /** * the OS resource for the Transform * (Warning: This field is platform dependent) * <p> * <b>IMPORTANT:</b> This field is <em>not</em> part of the SWT * public API. It is marked public only so that it can be shared * within the packages provided by SWT. It is not available on all * platforms and should never be accessed from application code. * </p> * * @noreference This field is not intended to be referenced by clients. */ public NSAffineTransform handle; /** * Constructs a new identity Transform. * <p> * This operation requires the operating system's advanced * graphics subsystem which may not be available on some * platforms. * </p> * <p> * You must dispose the transform when it is no longer required. * </p> * * @param device the device on which to allocate the Transform * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li> * </ul> * @exception SWTException <ul> * <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li> * </ul> * @exception SWTError <ul> * <li>ERROR_NO_HANDLES if a handle for the Transform could not be obtained</li> * </ul> * * @see #dispose() */ public Transform(Device device) { this(device, 1, 0, 0, 1, 0, 0); } /** * Constructs a new Transform given an array of elements that represent the * matrix that describes the transformation. * <p> * This operation requires the operating system's advanced * graphics subsystem which may not be available on some * platforms. * </p> * <p> * You must dispose the transform when it is no longer required. * </p> * * @param device the device on which to allocate the Transform * @param elements an array of floats that describe the transformation matrix * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device, or the elements array is null</li> * <li>ERROR_INVALID_ARGUMENT - if the elements array is too small to hold the matrix values</li> * </ul> * @exception SWTException <ul> * <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li> * </ul> * @exception SWTError <ul> * <li>ERROR_NO_HANDLES if a handle for the Transform could not be obtained</li> * </ul> * * @see #dispose() */ public Transform(Device device, float[] elements) { this(device, checkTransform(elements)[0], elements[1], elements[2], elements[3], elements[4], elements[5]); } /** * Constructs a new Transform given all of the elements that represent the * matrix that describes the transformation. * <p> * This operation requires the operating system's advanced * graphics subsystem which may not be available on some * platforms. * </p> * <p> * You must dispose the transform when it is no longer required. * </p> * * @param device the device on which to allocate the Transform * @param m11 the first element of the first row of the matrix * @param m12 the second element of the first row of the matrix * @param m21 the first element of the second row of the matrix * @param m22 the second element of the second row of the matrix * @param dx the third element of the first row of the matrix * @param dy the third element of the second row of the matrix * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if device is null and there is no current device</li> * </ul> * @exception SWTException <ul> * <li>ERROR_NO_GRAPHICS_LIBRARY - if advanced graphics are not available</li> * </ul> * @exception SWTError <ul> * <li>ERROR_NO_HANDLES if a handle for the Transform could not be obtained</li> * </ul> * * @see #dispose() */ public Transform(Device device, float m11, float m12, float m21, float m22, float dx, float dy) { super(device); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { handle = NSAffineTransform.transform(); if (handle == null) SWT.error(SWT.ERROR_NO_HANDLES); handle.retain(); setElements(m11, m12, m21, m22, dx, dy); init(); } finally { if (pool != null) pool.release(); } } static float[] checkTransform(float[] elements) { if (elements == null) SWT.error(SWT.ERROR_NULL_ARGUMENT); if (elements.length < 6) SWT.error(SWT.ERROR_INVALID_ARGUMENT); return elements; } @Override void destroy() { handle.release(); handle = null; } /** * Fills the parameter with the values of the transformation matrix * that the receiver represents, in the order {m11, m12, m21, m22, dx, dy}. * * @param elements array to hold the matrix values * * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * </ul> * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the parameter is null</li> * <li>ERROR_INVALID_ARGUMENT - if the parameter is too small to hold the matrix values</li> * </ul> */ public void getElements(float[] elements) { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); if (elements == null) SWT.error(SWT.ERROR_NULL_ARGUMENT); if (elements.length < 6) SWT.error(SWT.ERROR_INVALID_ARGUMENT); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { NSAffineTransformStruct struct = handle.transformStruct(); elements[0] = (float) struct.m11; elements[1] = (float) struct.m12; elements[2] = (float) struct.m21; elements[3] = (float) struct.m22; elements[4] = (float) struct.tX; elements[5] = (float) struct.tY; } finally { if (pool != null) pool.release(); } } /** * Modifies the receiver such that the matrix it represents becomes the * identity matrix. * * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * </ul> * * @since 3.4 */ public void identity() { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { NSAffineTransformStruct struct = new NSAffineTransformStruct(); struct.m11 = 1; struct.m22 = 1; handle.setTransformStruct(struct); } finally { if (pool != null) pool.release(); } } /** * Modifies the receiver such that the matrix it represents becomes * the mathematical inverse of the matrix it previously represented. * * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * <li>ERROR_CANNOT_INVERT_MATRIX - if the matrix is not invertible</li> * </ul> */ public void invert() { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { NSAffineTransformStruct struct = handle.transformStruct(); if ((struct.m11 * struct.m22 - struct.m12 * struct.m21) == 0) { SWT.error(SWT.ERROR_CANNOT_INVERT_MATRIX); } handle.invert(); } finally { if (pool != null) pool.release(); } } /** * Returns <code>true</code> if the Transform has been disposed, * and <code>false</code> otherwise. * <p> * This method gets the dispose state for the Transform. * When a Transform has been disposed, it is an error to * invoke any other method (except {@link #dispose()}) using the Transform. * * @return <code>true</code> when the Transform is disposed, and <code>false</code> otherwise */ @Override public boolean isDisposed() { return handle == null; } /** * Returns <code>true</code> if the Transform represents the identity matrix * and false otherwise. * * @return <code>true</code> if the receiver is an identity Transform, and <code>false</code> otherwise */ public boolean isIdentity() { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { NSAffineTransformStruct struct = handle.transformStruct(); return struct.m11 == 1 && struct.m12 == 0 && struct.m21 == 0 && struct.m22 == 1 && struct.tX == 0 && struct.tY == 0; } finally { if (pool != null) pool.release(); } } /** * Modifies the receiver such that the matrix it represents becomes the * the result of multiplying the matrix it previously represented by the * argument. * * @param matrix the matrix to multiply the receiver by * * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * </ul> * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the parameter is null</li> * <li>ERROR_INVALID_ARGUMENT - if the parameter has been disposed</li> * </ul> */ public void multiply(Transform matrix) { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); if (matrix == null) SWT.error(SWT.ERROR_NULL_ARGUMENT); if (matrix.isDisposed()) SWT.error(SWT.ERROR_INVALID_ARGUMENT); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { handle.prependTransform(matrix.handle); } finally { if (pool != null) pool.release(); } } /** * Modifies the receiver so that it represents a transformation that is * equivalent to its previous transformation rotated by the specified angle. * The angle is specified in degrees and for the identity transform 0 degrees * is at the 3 o'clock position. A positive value indicates a clockwise rotation * while a negative value indicates a counter-clockwise rotation. * * @param angle the angle to rotate the transformation by * * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * </ul> */ public void rotate(float angle) { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { handle.rotateByDegrees(angle); } finally { if (pool != null) pool.release(); } } /** * Modifies the receiver so that it represents a transformation that is * equivalent to its previous transformation scaled by (scaleX, scaleY). * * @param scaleX the amount to scale in the X direction * @param scaleY the amount to scale in the Y direction * * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * </ul> */ public void scale(float scaleX, float scaleY) { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { handle.scaleXBy(scaleX, scaleY); } finally { if (pool != null) pool.release(); } } /** * Modifies the receiver to represent a new transformation given all of * the elements that represent the matrix that describes that transformation. * * @param m11 the first element of the first row of the matrix * @param m12 the second element of the first row of the matrix * @param m21 the first element of the second row of the matrix * @param m22 the second element of the second row of the matrix * @param dx the third element of the first row of the matrix * @param dy the third element of the second row of the matrix * * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * </ul> */ public void setElements(float m11, float m12, float m21, float m22, float dx, float dy) { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { NSAffineTransformStruct struct = new NSAffineTransformStruct(); struct.m11 = m11; struct.m12 = m12; struct.m21 = m21; struct.m22 = m22; struct.tX = dx; struct.tY = dy; handle.setTransformStruct(struct); } finally { if (pool != null) pool.release(); } } /** * Modifies the receiver so that it represents a transformation that is * equivalent to its previous transformation sheared by (shearX, shearY). * * @param shearX the shear factor in the X direction * @param shearY the shear factor in the Y direction * * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * </ul> * * @since 3.4 */ public void shear(float shearX, float shearY) { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { NSAffineTransformStruct struct = new NSAffineTransformStruct(); struct.m11 = 1; struct.m12 = shearX; struct.m21 = shearY; struct.m22 = 1; NSAffineTransform matrix = NSAffineTransform.transform(); matrix.setTransformStruct(struct); handle.prependTransform(matrix); } finally { if (pool != null) pool.release(); } } /** * Given an array containing points described by alternating x and y values, * modify that array such that each point has been replaced with the result of * applying the transformation represented by the receiver to that point. * * @param pointArray an array of alternating x and y values to be transformed * * @exception IllegalArgumentException <ul> * <li>ERROR_NULL_ARGUMENT - if the point array is null</li> * </ul> * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * </ul> */ public void transform(float[] pointArray) { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); if (pointArray == null) SWT.error(SWT.ERROR_NULL_ARGUMENT); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { NSPoint point = new NSPoint(); int length = pointArray.length / 2; for (int i = 0, j = 0; i < length; i++, j += 2) { point.x = pointArray[j]; point.y = pointArray[j + 1]; point = handle.transformPoint(point); pointArray[j] = (float) point.x; pointArray[j + 1] = (float) point.y; } } finally { if (pool != null) pool.release(); } } /** * Modifies the receiver so that it represents a transformation that is * equivalent to its previous transformation translated by (offsetX, offsetY). * * @param offsetX the distance to translate in the X direction * @param offsetY the distance to translate in the Y direction * * @exception SWTException <ul> * <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> * </ul> */ public void translate(float offsetX, float offsetY) { if (isDisposed()) SWT.error(SWT.ERROR_GRAPHIC_DISPOSED); NSAutoreleasePool pool = null; if (!NSThread.isMainThread()) pool = (NSAutoreleasePool) new NSAutoreleasePool().alloc().init(); try { handle.translateXBy(offsetX, offsetY); } finally { if (pool != null) pool.release(); } } /** * Returns a string containing a concise, human-readable * description of the receiver. * * @return a string representation of the receiver */ @Override public String toString() { if (isDisposed()) return "Transform {*DISPOSED*}"; float[] elements = new float[6]; getElements(elements); return "Transform {" + elements[0] + ", " + elements[1] + ", " + elements[2] + ", " + elements[3] + ", " + elements[4] + ", " + elements[5] + "}"; } }